Fan



Jan. 9, 1940.-

D MCMAHAN 2,186,837

FAN

Filed March 30, 1937 Inventor:

y Ha /attorney.

Kenton D.I"k:I"lal'1ar-1,

Patented Jan. 9, 1940 UNITED "STATES FAN Kenton D. McMahan, Schenectady, N. 1.,-

, signor to General Electric Company, a corporation of New York Application March 30, 1937, Serial lilo. 133,842

6 Claims.

My invention relates to fans and more particularly to fans for circulating air through a radiaton An object of my invention is to provide an 5 improved fan of the propeller type adapted to circulate air against a back pressure.

Another object of my invention is to .provide a fan which will operate efllciently throughout a range of speeds and against a varying back 10 pressure.

What I consider to be novel and my invention will be better understood by reference to the following specification and appended claims when considered in connection with the accompanying 1 drawing in which Fig. 1 is a side elevation of a fan-mounted between an automobile engine and radiator; Fig. 2 is a perspective view of the fan and radiator; and .Fig. 3 shows difierent curves of flow against diflerent static pressure.

50 Referring to the drawing, l0 indicates an automobile engine on which is mounted a fan H, adapted to be driven thereby and positioned to circulate air through a radiator, 12. In the operation of an automobile the fan is driven by 35 the engine at varying speeds depending upon the speed of the car and the ratio of the gears interconnecting the driving means for the fan and the engine.' When the engine is idling the fan is driven at a relatively low speed and the air circulated through the radiator i2 depends upon the radiator resistance and the speed of rotation of the fan.

Referring to Fig. 3, curve A indicates the variation of air flow-with the static pressure of a fan circulating -air through a radiator.

represents-the resistance of the radiator. The

intersection of curves A and Cindicated by the numeral l3 represents the air flow through the 'r'adiator when the car is idling. When the car the car and the operation of the fan at a higher speed produces a flow of air which is represented in Fig. 3 by the numeral H. Pvj is the pressure head due to the motion of the car. The com- 5 blned pressure head produced by the fan and the eral l5 shows a higher air-flow when the car is "idling. However, when the car is in motion producing a'pressure head I'v, the total air flow is moving, the combined action of the motion of indicated by the numeral I! is less than the flow produced by the fan alone. Thus, from these curves it may be seen that a tan alone 'wi1lpro-, duce a greater-flow when the car is running and the combination of a fixed cowling and fan will 5 produce a greater flow when the car is standing or idling.

4 I have found that the advantage of a greater flow when the car is running of the Ian alone and the greater flow of the combination of the-fixed l0 cowling and fan when idling can be obtained by a cowling l'l secured to the periphery of the fan and consisting of a housing portion I 8 tapering to an orifice l9 integrally connected thereto. The housing portion it determines'the portion 15 of the radiator through which the fan alone will circulate air and the orifice I 9 produces a smooth flow through the fan and thus increases the amount of air which can be circulated by the fan without turbulence and against a higher back m pressure. When the car is standing theamount of air which can be circulated through the radiatordepends upon the speed of the fan and the portion'oi the radiator blocked out by the housing l8. When the car is in motion the air under 55 the influence of the tan and the motion of the carcombined will'be determined by the portion of the radiator blocked out by the housing and the motion of the car'alone will produce anadditional flow through the remainder of the so radiator. The housing, in addition to determining the portion 01' the radiator through which. air will be circulated by the fan also prevents a recirculation of air adjacent'the outer periphery Curve C 01' the fan as commonly experienced in the as operation of a fan alone due to the great diflerence in the pressure produced at the tip of the fan and adjacent to the fan. The recirculation oi air or eddies produced at this point greatly reduces the flow of air through the radiator espeo ciall when the car is standing and also increases the amount of power necessary to drive the fan to produce a desired flow through the radiator. The spacing between the radiator l2 and housing I8 .is just suflicient to insure that the vibra- 4,5 tion of the engine will not produce a contact between the'rotating' housing l8 and the stationary radiator I2. In Fig. 2 the'reiation between the portion of the radiator l2 blocked out by the housing I8 is better indicated. The ratio be- 50 tween the blocked out portion and the remainder v of the radiator is determined by the diameter of the fan, the size of the radiator and the relation between the flow desired whenthe car is idling and that necessary "when the car is in motion. 5

Curve D of Fig. 8 shows the air flow of the combination of fan and rotating cowling. As may be seen from this curve, the air flow when the car is standing is substantially the same as the air flow produced by the combination ora nxed cowling and a separate fan and at running speeds the air flow represented by curve D is substantially the-same as the air flow of a fan alone operating in combination with a radiator.

The provision of a housing l8 with an enlarged inlet opening tapering inwardly to'an orince l9 directly secured to the periphery 'ofthe fan permits the use of a smaller diameter fan as it increases the area oi influence of the fan. As pointed out above, a fan operating alone adjacent a radiator is limited by the recirculation 01 air or eddies produced adjacent the tip of the fan both in the amount 01' air which it can circulate and the area of the radiator which it can effect. The energy consumed in the operation of the fan is also reduced by eliminating these eddies as it has been found that these .eddies consume considerable power and to nopurpose. The use of a cowling secured directly to the fan blades has the advantage over the combination of a fixed cowling and fan in that the. eiliciency-of the combination depends upon a minimum spacing between the cowling and fan. Obviously, in auto mobile operation it is difficult to make such a spacing very small. On the other hand, when the cowling is secured directly to the fan the combination operates eiilciently and the spacing between the cowling and the radiator can be made more than suii'icient to allow for vibration of the engine without affecting, the operation 01 the combination.

In the above specification I have described the use of a combined fan and cowling with an automobile engine and radiator. My invention is not limited to the use of a ian'and cowling secured to the blades in such a combination alone as it may to advantage be used in combination with a fixed mountingand radiator such as-in an air conditioning apparatus or for-any operation in which the fan must circulate air against a back pressure with a resultant highly efllcient and improved operation.

What I claim as new and desire to secure by Letters Patent 01 the United States is:

1. In combination, a radiator, a tan positioned adjacent said radiator and adapted to draw a fluid through said radiator, means for driving said fan, and a cowling secured to the periphery of the tan and having an enlarged inlet opening adjacent said radiator.

2. In combination, a radiator, a tan positioned adjacent said radiator and adapted to draw air through the radiator, means to drive said fan, and a housing secured to said fan, adapted to rotate therewith and having an enlarged inlet opening adjacent said radiator.

3. In combinatioma radiator and means for 4. In a vehicle, a radiator subject to a pressure head due to the velocity of the vehicle forcing air through the radiator from the front to the rear, and a fan at the rear of the radiator arranged to draw air through the radiator irorn the front to the rear, said fan comprising a plurality of fan blades and a cowling secured to the periphery of the blades having an enlarged inlet opening adjacent the radiator andtapering to an orifice at the periphery of the blades.

5. In a vehicle, a radiator subject to a pressure head due to the velocity of the vehicle forcing air through the radiator from the front to the rear, and a fan at the rear of the radiator arranged to draw air through the radiator from the front to the rear, said fan comprising a plurality of fan blades and a cowling secured to the periphery of the blades having an enlarged inlet opening adjacent the radiator and an outlet opening of substantially the same diameter as the tan.

6. In a vehicle, a radiator subject to a pressure head due to the velocity 01' the vehicle forcing air through the radiator from theiront to the rear, and a fan at the rear of the radiator arranged to draw air through the radiator from the front to the rear, said fan comprising a plurality oi. blades, an orifice secured to the periphery of the blades, and a housing connected to said orifice and having an enlarged inlet opening adjacent the radiator. I

BENTON D. MCMAHAN. 

